Lindcott Armory Wildcat · Wildcat
.300 Whisper
The .300 Whisper is a wildcat cartridge developed by J.D.
- Caliber
- 0.3084″ · 7.833 mm
- Introduced
- 1992
- Case
- Rimless
- Parent
- .221 Remington Fireball
- Primary use
- suppressor_use, hunting_small_game, military_special_operations
- Status
- Obsolete
- Introduced
- 1992
- Type
- Wildcat
- Origin
- United States
- Inventor
- J.D. Jones
- Manufacturer
- SSK Industries
- Standard
- Wildcat
- Status
- Obsolete
- Availability
- Handload Only
- Case capacity
- 26.5 gr H₂O
- Twist (typical)
- 1:8
- Primer
- Small Rifle
- Case type
- Rimless
- Max pressure
- 25,000 psi
- Eff. range
- 250 yd
- Recoil
- 4–7 ft·lb
- Subsonic
- Capable
Ballistics
- By real loads
- 1,000–2,375 fps · 14 loads
- Parent case
- .221 Remington Fireball
Representative trajectory — modeled from a single velocity input (no published BC for this cartridge yet).
Performance
Buy links open .300 Whisper ammunition at Rivertown Munitions.
Dimensionscase measurements · scale drawing · size vs familiar rounds
Case dimensions — the scale drawing at the top of the page is built from these.
CIP TDCC · approximate| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 7.83 | 0.308 | ✓ |
| Neck ⌀ | 8.46 | 0.333 | ✓ |
| Shoulder ⌀ | 9.14 | 0.360 | ✓ |
| Shoulder angle | 23° | — | ✓ |
| Base ⌀ | 9.54 | 0.376 | ✓ |
| Rim ⌀ | 9.60 | 0.378 | ✓ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.14 | 0.045 | ✓ |
| Neck length | 6.75 | 0.266 | ≈ |
| Case length | 34.82 | 1.371 | ~ |
| Overall length | 57.20 | 2.252 | ~ |
Size vs familiar rounds
Drawn at true 1:1 — every case is accurate relative to the others. Absolute size depends on your screen's pixel density, so measuring one against a real ruler may be off. .300 Whisper is highlighted below.
Factory loads
In production — 14 active loads across 12 brands. Top 15 shown · see all 20 →.
| Brand | Load | Grain | Bullet | FPS | ft·lb | BC |
|---|---|---|---|---|---|---|
| Hornady | Custom | 110 | V-Max | 2,375 | 1,377 | — |
| Black Hills | Supersonic | 110 | OTM | 2,375 | 1,377 | — |
| SIG Sauer | Elite | 125 | OTM | 2,175 | 1,313 | — |
| Remington | Range | 125 | FMJ | 2,175 | 1,313 | — |
| Hornady | Subsonic | 190 | Sub-X | 1,050 | 465 | — |
| DoubleTap | Subsonic | 220 | JHP | 1,040 | 528 | — |
| Doubletap | Subsonic | 220 | Hollow Point | 1,020 | 508 | — |
| Wilson Combat | Subsonic | 220 | FMJ | 1,010 | 498 | — |
| SilencerCo | Omega | 220 | Hollow Point BT | 1,010 | 498 | — |
| HSM Ammunition | Subsonic | 220 | Hollow Point BT | 1,010 | 498 | — |
| Black Hills | Subsonic | 220 | Hollow Point BT | 1,010 | 498 | — |
| Engel Ballistic Research | Subsonic | 220 | Hollow Point | 1,000 | 488 | — |
| PPU | Subsonic | 220 | FMJ | 1,000 | 488 | — |
| Wolf | Subsonic | 220 | FMJ | 1,000 | 488 | — |
| Nosler | Custom HP BT Supersonic | 125 | HPBT | 2,200 | 1,343 | 0.502 G1 |
Velocities are manufacturer-stated (test-barrel). Discontinued loads dimmed.
Reloading costestimate cost per round vs factory
Estimate your cost per round and how it compares to factory. Inputs are yours — nothing is stored.
Cost estimate only — not load data. Charge weight is your input; follow published manuals for safe charges.
Firearms chambered in .300 Whisper
1 model in the database chamber .300 Whisper. Browse all →
Lineage
Connected reference
History
J.D. Jones designed the Whisper concept around the .221 Remington Fireball case, which fits in a standard AR-15 bolt face while providing enough case capacity for heavy .30-caliber subsonic loads. The cartridge gained a following in military special operations communities and among suppressor enthusiasts. Advanced Armament Corporation (AAC) later developed the .300 AAC Blackout as a SAAMI-standardized version with input from the military, achieving essentially the same ballistics with standardized dimensions.
FAQs
- What twist rate does .300 Whisper use?
- .300 Whisper typically uses a 1:8 twist rate.
- What bullet diameter is .300 Whisper?
- .300 Whisper uses a 0.3084″ (7.833 mm) diameter bullet.
- Is .300 Whisper still in production?
- .300 Whisper is obsolete; typical availability is handload only.
- What is .300 Whisper used for?
- .300 Whisper is primarily used for suppressor_use, hunting_small_game, military_special_operations.
- What is .300 Whisper based on?
- .300 Whisper is derived from the .221 Remington Fireball case.
Sources & provenance
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 14 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →